1. Field of Invention
The present invention relates an improved fully automatic scraper grinder and, in particular, to a grinder that comprises an emery wheel base, a set of upper and lower fine tuning devices driven by a motor provided thereon, and a set of front and back two-step displacement device driven by a cylinder. By incorporating a specially designed emery wheel with two different sizes of emery on the front and back, the emery wheel can provide a set of fully automatic grinding procedure that can first roughly grind then finely grind according to different scrapers using a digital control system. Furthermore, a worm type angle adjuster is provided on a scraper holder for adjusting the angle of the scraper holder, an automatic switching aspirator is provided on the emery wheel base for automatic switches to single sided air intake in the reciprocating motion of the emery wheel to remove the dusts produced by the scraper grinding.
2. Related Art
Since currently all scraper (i.e., the ink scraper used in the halftone printing) grinders in the world are of the semi-automatic type; namely, an operator has to operate and monitor while grinding so as to control the scraper in an automatic cycle of the emery wheel. Furthermore, currently used grinding wheels are emery wheels or emery stripes. It is very lately that a U.S. made diamond emery wheel is available. However, since scrapers need to be finely ground, small diamond particles have to be employed. Each time the scraper is inserted into the emery wheel with diamond granules by 0.1 to 0.2 mm. If the scraper is inserted too much, then the grinding surface would be overheated so that the scraper or dusts become sticky and affect the quality of the scraper and the grinding surface of the emery wheel. Nevertheless, each scraper has 0.2 to 10 mm to be ground, so the scraper has to be inserted several times to complete the whole grinding process. This is a very time-wasting and tiring job, which is one defect of the conventional scraper grinder.
Moreover, dusts will be produced while grinding the scraper. Therefore, the scraper grinder is always provided with a dust remover. Since the scraper is ground by moving the emery wheel sideways reciprocally, the emery wheel motor also switches its rotational directions in this reciprocal process. When the emery wheel grinds in one direction, the dusts are exhausted to the other. So the air intake pipe of the conventional dust aspirator has a main sucking pipe that is divided into two side pipes on both sides of the emery wheel and sucking at the same time. The suction is thus divided in halves and appears to be insufficient. It can roughly obtain 60% of the dust removing effect, which is another defect of the conventional scraper grinder.
The scraper grinder is equipped with a scraper holder, which can be turned and adjusted to a proper grinding angle. Yet, conventionally the angle adjustment of the scraper holder is done manually. When the holder is too long or the operator is female, it is hard to hold and operate, which in turn affect the precision of the scraper grinding angle. This is the other defect of the conventional scraper grinder.